Production of alkyl resorcinols



Patented Jan. 1, 1929.

UNITED STATES PATENT ounce; A

ALFRED R. L- DOHME, OI BALTIMORE, MARYLAND, ASBIGNOR 'IOSHARP G; DOHME, INC., IBALTIIIORE, MARYLAND, A CORPORATION OF NEW JERSEY.v

PRODUCTION OF ALKYL RESORGINOLS.

No Drawing. Application filed Api'll 18, 1925, Serial No. 23,701. Renewed OctoberBl, 1928.

This invention relates to an im roved method of making alkyl resorcinols, including not only the lower alkyl resorcinols such as ropyl and butyl resorcinols, but also the big er alkyl resorcinols, such as amyl, hexyl,

heptyl, octyl, dodecyl resorcinols, etc.

The present invention relates particularly to the production of alkyl resorclnols from acyl resorcinols which maybe obtained in high yields by condensation of resorcinol and fatt acid with zinc chloride for example, by

gra uall adding resorcinol to a heated mixture of Z1110 chloride and fattyacid with agitation of the mixture and with maintenance of the temperature of the reaction mixture at about 125145 C. and with the use of a small amount of zinc chloride which may be only asmall fraction of the weight of the fatt acid, e. g., around one-fifth the weight of to acid. The acyl resorcinol can be obtained inthis way with the avoidance of any large amounts of tarry by-products and in a form such that it can be further treated with aminimum of purification for the production of the alkyl resorcinol. The acyl resorcinol can be purified, if necessary or desirable, before using it. It is not necessary to obtain a product of the highest purity but the acyl resorcinol produced in the form of an oil can advantageously he used for the production of alkyl resorcinol in accordance with the present invention. Where this oil is not of suflicient purity it can be further purified, e. g., by redistlllation, crystallization from solvents, etc. Instead of using acyl resorcinols produced in this way, acyl resorcinols otherwise produced and of suit able purity may be used in. accordance with the improved process of the invention for the making of alkyl resorcinols therefrom. That is, the improved process of the invention ma make use of acyl resorcinols produced in any suitable way; but it may aduse an amount of zinc amalgam equal to about eight times the weight of the acyl resorcinol,

together with about 5 parts of hydrochloric acid and 5 parts of water. This reaction is not only slow, requiring about twenty-nine hours at the boiling point of the reduction mixture, but further amounts of hydrochloric acid must he added during the progress of the reaction.

According to the present invention, a radicall reduced amount of zinc amalgam is usec and the reduction is effected in a greatly reduced period of time. In the present process the amount of zinc amalgam is reduced to about two and one-half times the weight of the acyl resorcinol, and the reduction is carried out with vigorous agitation of the reduction mixture.

In carrying out the present process, for example, one part by weight of theacyl resorcinol. is reduced by about twoand onehalf parts by weight of zinc amalgmn, using about tive pa-rts of hydrochloric acid (20" B6.) and about six parts of water, and the reduction mixture being vigorously agitated and maintained at a temperature of about 105" C. By proceeding in this way the reduction is finished in about ten to twelve hours. The reduction product may then be washed with an equal volume of water and then distilled in vacuo, whereby the water is first distilled off and finally the alkyl resorcinol.

The zinc amalgam is made by amalgamating mossy zinc with. a 2% solution ofimercuric chloride. The completion of thereduction may be readily determined by testing a few drops of the oily product dissolved in a' few cc. of alcohol with a drop of ferric chloride solution. When the reduction is com- 'pleted, no red coloration will-be shown by this test.

The improved reduction process of the present invention isnot only effected in a eriod of time, but 1ves I the roduction of hexyl resorcinol.

hile the pure crystalline hexylyl resorcinol can be used'for the production therefrom of hexyl resorcinol,- it is not necessaryto use the hexylyl resorcinol in a pure state.

The method of reduction will be illustrated by the following exam le: One part by weight 0 hexylyl resorcinol is reduced by 2 parts of zinc amalgam in five parts of hydrochloric acid (20 B.) and six parts of water, with vigorous stirring at about 105. The reduction is complete in ten to twelve hours. The reduction product is washed with an equal volume ofqvater and the water layer separated. The reduction product is then distilled in vacuo whereby the last traces of water are removed and finally the hexyl resorcinol is distilled. It has In a similar way other alkyl resorcinols can a .be produced from the intermediate ketones.

Among the alkyl resorcinols which can be thus obtained may be mentioned the following, the melting point and boiling point in degrees centigrade ofeach compound in a purified state being given:

It will thus be seen that the present invention provides an improved process of making alkyl resorcinols in high yield from acyl resorcinols with the use of radically reduced amount of zinc amalgam and with vigorous agitation of the reduction mixture whereby the reduction is completed in a greatly shortened period of time.

The improved process is applicable not only fto the production of the lower alkyl resorcinols, certain of which have been heretofore known and produced, but also and particularly to the production of the new higher alkyl resorcinols.

I claim: p

1. The method of-making alkyl resorcinols which comprises subjecting acyl resorcinols to reduction with zinc amalgam and hydrochloric acid, the amount of zinc amalgam not exceeding about two and one-half times the weight of the acyl resorcinol, and the reduction being effected with vigorous agitation of the mixture-at a reactive tem erature.

2. The method of making iexyl resorcinol which comprises subjecting hexylyl resorcinol to reduction with zinc amalgam and hydrochloric acid, the amount of zinc amalgam not exceeding about two and'one-half times the weight of the hexylyl resorcinol, and the reduction being effected with vigorous agitation of the mixture at a reactive temperature.

- 3. The method of making hexyl resorcinol which comprises subjecting hexylyl resorcinol to reduction with zinc amalgam and hydrochloric acid, the amount of zinc amalgam not exceeding about two and one-half times the weight of the hexylylresorcinol, and the riduction being efl'ected with vigorous agitation of the mixture at'a temperature of about 105 C.

In testimony whereof I aflix my signature.

ALFRED R. L. DOHME. 

